Among Colorado's longest mountain chains, the Gore Range stretches nearly 100 miles from its northern terminus near Steamboat Springs to its southernmost slopes near Climax. The northern portion of the Gore Range makes up part of the larger Park Range which extends northward nearly to the Wyoming border. The Sierra Madre Range takes up where the Park Range leaves off, continuing northward well into Wyoming. Throughout most of the length of the Sierra Madre, Park, and Gore Ranges, Precambrian igneous and metamorphic basement rock forms the core of the mountain chain. Indeed, the trend continues southward as both the Tenmile and Mosquito Ranges harbor ancient Precambrian crystalline rocks at their core.
Like most Colorado mountains, the Gore Range is an uplifted, fault-bounded anticlinal structure that trends roughly north-south and which contains ancient Precambrian basement rock at its heart. The Gore Range differs from most other ranges in that a few remnants of the overlying sedimentary rocks that once draped the Precambrian core still remain on top of the range. In most other ranges the sedimentary cover has been stripped away as a result of uplift and erosion.
Throughout most of its length, the Gore Range consists of ancient Precambrian gneisses and schists intruded by slightly younger 1.7 billion year old granites. These Precambrian crystalline rocks are exposed in the uplifted cores of many of Colorado's mountain ranges and are some of the oldest rocks in the state. Along both flanks of the Gore Range, younger sedimentary rocks lap up against the Precambrian core. These sedimentary
The Gore Range is bounded by 2 major fault zones. On its western side, the Gore Fault separates the uplifted mountain block from the adjoining sediments; to the east, the Blue River Frontal Fault forms the boundary. Like the mountain range itself, these faults both trend in a northwest-southeast direction. In the center of the Gore Range, near the Colorado River and Gore Pass, a set of northeast-southwest trending faults cuts across the mountains. These faults are nearly perpendicular to the Blue River and Gore Faults.
Mineralization in the Gore Range is sparse and spotty. At its northern and southern extremities, rich mineral deposits occur, but throughout most of the range bonanza-quality ores are nonexistent. Indeed, the only gold-producing district of any note within the Gore Range is the Red Dirt District, which is located about 10 miles northwest of Gore Pass. Unfortunately, the district was never a big producer.
Due to the prohibitive size of the area of interest, prospectors should probably narrow their search to the areas that have produced indications of gold in the past and in which the geology is favorable for gold emplacement. These include (from north to south):
The Rabbit Ears Pass area figures prominently in a number of lost mine tales. In addition, the mountains just north and west of the pass are home to several Tertiary intrusive bodies. Prospectors may want to concentrate on these igneous intrusions first, paying special attention to the halo of baked and altered rock surrounding them. The adjacent unaltered country rock should also be carefully checked.
The headwaters of Red Dirt Creek are known producers of placer gold, albeit in small amounts. Nevertheless, a small exposure of gold-bearing ore must almost certainly lie somewhere upslope or upstream from the placers. Prospectors may want to focus on the crest of the Gore Range, between the Red Dirt Creek watershed (which flows eastward to Muddy Creek) and the Silver Creek drainage (which flows westward to the Yampa River).
The Gore Pass area is also mentioned in a number of lost mine accounts involving both gold and silver veins. The area is highly faulted and this, combined with its rich history of lost mines, makes it attractive to the modern-day prospector. Gold-seekers may want to concentrate on the fault zones in their search for the hidden ledge.
The headwaters of Piney River provided the backdrop for one of the first discoveries of gold in the Gore Range during the 1850's. It was while camping in the area that a member of Sir George Gore's famous expedition found a nugget of gold. Prospectors may want to work the streams near Piney Lake, looking for color. The source of that gold must certainly lie somewhere in the mountains surrounding the lake.
Finally, the southern end of the Gore Range has already been shown to be mineralized to some extent. In addition, the world-famous Climax molybdenum deposits lie just south of the range near Fremont Pass. The small Laramide intrusions that crop out along the southern end of the Gore Range are certainly worthy of attention. These small plutons intrude the Pennsylvanian-Permian red beds that drape the Precambrian core of the Gore Range on its southernmost end.